So there's a 700nm torque limit for the DCT

amc · 6th February 2012, 21:30

The magazine "European Car" quotes BMW's Helmut Gehring saying "The new gearbox has a 700 Nm torque capacity". See scanned article here: NEW European Car Magazine Review M5 F10 (Jan/Feb 2012) - 2010 2011 BMW 5 Series Forum F10

I checked with the technical data from Getrag's German website, and they too specify a maximum torque of 700 Nm. As the regular M5 already is specced at 680nm, this means there's a real limit for engine tuning.

The details are probably more complex and there are probably combinations of gear and rev speed where the DCT can take a higher torque. But from the available data we have, this means: whenever somebody offers engine tuning for the M5, customers should ask the question: "ok, and how do you deal with the DCT?".

MTV10 · 6th February 2012, 21:53

Simple: Get the 6 speed

amc · 6th February 2012, 23:07

For US cars, maybe. I don't know the specs of the manual transmission yet. Spies, report back to base!

Then again, even if the spec for manual is any higher, the rear differential and other parts of the drive train will be the next questions. With the DCT limit at 700nm, that also means nothing else needs to be engineered to work with higher torque.

BMWDave · 6th February 2012, 23:49

If what they are saying is true then something doesn't add up.

Apparantely the people at PP Performance claim to have created the first ECU tune for the F10 M5 and are producing 750nm of torque. Thusly it is sufficient to say that either they are lying or really have acheived 750nm and their DCT is going to break any day now.

PP-Performance: BMW M5 (F10) tuning 620HP and 750Nm

Time will tell I guess.

clarence · 7th February 2012, 01:05

Quote:

Originally Posted by BMWDave

If what they are saying is true then something doesn't add up.

Apparantely the people at PP Performance claim to have created the first ECU tune for the F10 M5 and are producing 750nm of torque. Thusly it is sufficient to say that either they are lying or really have acheived 750nm and their DCT is going to break any day now.

PP-Performance: BMW M5 (F10) tuning 620HP and 750Nm

Time will tell I guess.

700 NM limit is absolute bulls. No manufacturer worth its salt would engineer a high performance car with so little buffer in its mechanicals.

Javacore99 · 7th February 2012, 01:57

I like how there is a new version of perceived limitations with this car every now and then..

So far i recall in no particular order:

1. No DCT since DCT cannot handle additional tq from engine.. so we were supposed to get 8sp Auto
2. Crankshaft design could not handle power from engine so car was detuned.. no evidence of this
3. Car is not tunable since car is already running max boost and any changes will result in engine failure.. see PP performance for 620hp and 750nm with just tune

You get the idea and i could go on.. No one really knows until G-Power or some other tuner gets insane figures from this car.. I see 620hp and 750nm as a start. Nothing is untunable..just how much money you are willing to spend.

ideliver · 7th February 2012, 02:08

The G power M3 tornado puts down 720 hp and 700 Nm of torque.

amc · 7th February 2012, 09:33

Quote:

Originally Posted by Javacore99

I like how there is a new version of perceived limitations with this car every now and then..

So far i recall in no particular order:

Comparing manufacturer statements and OEM spec with unfounded speculations is a bit weird. If Getrag says their DCT is certified for up to 700 Nm, then it is. One could argue BMW uses a modifies version, but as the number has been stated by one of BMWs engineering heads, too, it appears the spec listed by Getrag already is the M5 spec.

And as for tuning: of course the 700nm isn't a hard limit. It just means the DCT has been designed to sustain that torque for the design lifetime of the car. Even a tune to "only" 750nm is something that I would be very careful about if one wants the car to reach a high mileage. BMW has stated in said article that they basically used the DCT from the M3 with a number of stronger materials in order to not increase the weight too much. That certainly doesn't sound like an overengineered part with lots of buffer.

The replacement DCT for the M3 already is a 10K item. Just make sure a tuning company offers a warranty that covers that. And do read the fine print.

FTB · 7th February 2012, 11:00

The thing is that you CAN replace the DCT clutches with better ones.
I've read about it on M3Post and a member with an ESS VT3 SC upgraded the clutches. Problem solved.

amc · 7th February 2012, 12:50

To repeat: I didn't say there's no way. What I said was: "whenever somebody offers engine tuning for the M5, customers should ask the question: "ok, and how do you deal with the DCT?".

Any reasonable answer is ok.

Regarding the clutch upgrade: the question is where the limit is on the M5 unit. Is it only the clutches or do other parts also need reinforcing? It's specced as a complete DCT unit. I'm not sure anyone can solve this without dealing with Getrag directly.